Swash-plate pump or motor



March 27, 1962 J. BINHACK SWASH-PLATE PUMP OR MOTOR Filed Oct. 17, 1957 United States Patent 3,026,814 SWASH-PLATE PUMP R MOTOR Josef Binhack, Markstrasse 11, Neuenburg, Germany Filed Oct. 17, 1957, Ser. No. 690,665 Claims priority, application Germany Oct. 29, 1956 3 Claims. (Cl. 103-162) t The present invention relates to pumps or fluid motors.

More particularly, the present invention relates to swash-plate pumps or motors.

Swash-plate pumps or motors may be of the closed or open type. In the open type of swash-plate pump or motor the several pistons communicate with the medium surrounding the pump. However, such open-type swashplate pumps have several disadvantages. In pumps of this type the cylinder drum is rotatably supported by a support frame which has a pair of opposed pivot pin portions supported in suitable bearings so that the frame and rotary drum are turnable about the common axis of the pivot pin portions in order to regulate the strokes of the pistons. Because of the high pressure of the fluid of such a pump or motor, the walls which carry the bearings become deformed and move apart from each other so as to undesirably destroy the seal of the fluid passages of the pump. The frame which supports the cylinder drum for rotation is provided with passages for leading the fluid to and from a control surface of the frame provided with arcuate openings for the entrance and exit of the fluid to and from the cylinders of the cylinder drum, the latter having an end face which slides along the control surface during rotation of the cylinder drum. Because of the high pressure in the passages of the cylinder drum supporting frame the latter also becomes deformed and destroys the seal of the fluid passages.

One of the objects of the present invention is to provide a swash-plate pump or motor of the open type with a means which will reliably prevent movement of the bearings of the cylinder drum supporting frame apart from each other so that the seal can be properly maintained.

Another object of the present invention is to provide a swash-plate pump or motor which will reliably prevent the supporting frame itself from becoming deformed due to high pressures in the fluid passages of the supporting frame.

It is also an object of the present invention to provide structure capable of accomplishing the above objects and at the same time composed of simple and ruggedly constructed elements which are very reliable in operation.

With the above objects in view the present invention includes in a swash-plate pump or motor a cylinder drum and a support frame supporting the cylinder drum for rotation about its axis. This frame has a pair of coaxial pivot pin portions extending from opposed parts of the support frame and defining a turning axis for the frame and cylinder drum, the common axis of the pivot pin portions being normal to the axis of the cylinder drum. A pair of bearing means respectively cooperate with the pair of pivot pin portions and are carried by a suitable support member, and adjacent to the pair of bearing means the support member is provided with a pair of elongated substantially rigid members each of which is connected at its opposite ends to the pair of bearing means so as to prevent the latter from moving apart from each other under the influence of the pressure of the fluid. These elongated substantially rigid members which thus prevent movement of the bearings apart from each other and in this way maintaining the seal of the pump or motor are spaced from the rotary drum and frame by a distance sufficient to provide the desired degree of turning movement of the drum and frame about the common axis of the pivot pin portions.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings in which:

FIG. 1 is a sectional elevational view of a swash-plate pump or motor according to the present invention, the section of FIG. 1 being taken along a central plane of the structure; and

FIG. 2 is an end view of the structure of FIG. 1 as seen from the right side of FIG. 1.

As is apparent from the drawings, the pump or motor illustrated therein includes a driving or driven shaft 15 which is fixedly connected with the swash-plate 16. The several pistons 17 are connected with the swash-plate 16 in a conventional manner as through ball and socket joints 2%. The several pistons are respectively slidable in cylinder bores formed in a cylinder drum 18 which is rotatably supported for rotation about its axis. by a support frame member 1 which is turnable together with the drum 18 about an axis perpendicular to the axis of the shaft 15. The right end of the drum 18, as viewed in FIG. 1, cooperates with the control surface of the support frame 1 which is formed with openings 19 through which the hydraulic fluid flows to and from the interior of the cylinder bores of the drum 18.

The frame 1 herein also termed the open frame has a pair of opposed, coaxial pivot pin portions 2 which are respectively supported for turning movement by a pair of bearing means 3 which carry a pair of ball races 21 and which are fixed with a stationary support member 4 in the illustrated example. The pivot pin portions 2 whose common axis defines the axis about which the frame 1 and the drum 18 are turnable in order to adjust the strokes of the pistons, are axially bored so as to be provided with passage portions 5 through which the fluid moves to and from the cylinder drum. The upper bearing means 3 of FIGS. 1 and 2 carries an element 6 which serves to connect the passage 5 with a suitable conduit for the hydraulic fluid, and this conduit may be connected through threads or the like with the connecting member 6. The fluid-tight communication between the passage of member 6 and the passage 5 is provided with a sleeve 7 which extends into the passage 5 and which permits turning of the frame 1 with respect to the member 6 while maintaining a fluid-tight connection between the passage of frame 6 and the passage 5.

As was mentioned above, the seal of the passages is often destroyed at high pressures. This is brought about by the force exerted by the fluid under pressure between the points 9 and 10 indicated in FIG.. 1. As a result of this force the bearing means 3 become deformed so that they move apart from each other and there is no longer the desirable seal at the sleeve 7 In order to prevent this deformation, the pair of hearing means 3 for the pivot pin portions 2 are interconnected, according to the present invention, at opposite sides of the frame 1 and drum 18 by a pair of elongated substantially rigid members 11, as shown in FIGS. 1 and 2. These members 11 extend from the stationary support member 4 by such a distance that they do not in any Way interfere with the desired range of turning movement of the frame 1 and drum 18 about the common axis of the pivot pin portions 2. As is particularly apparent from "FIG. 1, each of the elongated rigid members 11 is cut away along its right edge, as viewed in FIG. 1, so that each of these members 11 tapers toward its intermediate portion and has a minimum width at its intermediate portion so as to provide in this way additional clearance for the turning of the frame 1 and drum 18 therewith.

Also, in order to provide a particularly effective stiffening of the pair of bearing means 3, the elongated members 11 are preferably joined along the entire length of their left edges, as viewed in FIG. 1, to the stationary support member 4, as by being welded thereto. Also, it is possible to make the members 11 integral with the support member 4.

According to another expedient in accordance with the present invention the pair of bearing means 3 can each extend beyond each pivot pin portion 2 laterally to an extent sufiicient to enable the pair of elongated rigid members 11 to be substantially straight while still being spaced from the frame 1 and drum 18 by a distance suflicient to permit the desired turning movement thereof.

The frame 1 has at opposite sides of the cylinder drum 18 elongated portions extending axially along the cylinder drum 1S and respectively formed with the passages 12 and 13 which respectively lead from the passages to the passages 19. Experience has shown that the seal of the passages is also destroyed in some cases because of deformations of the frame 1 resulting from great pressures in the passages 12 and 13. In order to avoid this latter type of deformations, the support frame 1 is preferably provided with side wall portions 14 which extend between and are fixed rigidly with the elongated frame portions provided with the passages 12 and 13. Each of the side wall portions 14 of the frame 1 extends from the right end thereof, as viewed in FIG. 1, to a point beyond the turning axis provided by the pivot pin portions 2, and as is apparent from FIG. 1 the left edge of each of the side wall portions 14 is arcuate so that there remains between the support member 4 and the side walls 14 an open space permitting free communication between the pistons 17 and the medium surrounding the pump motor. The side wall portions 14 preferably form cylinders and participate in the supporting of the cylinder drum 18 for rotational movement. Thus, the side walls 14 together wit-h the remainder of the frame 1 form a cylinder in which the drum 18 is supported for rotation, but this cylinder terminates short of the support member 4 so as to still maintain the open-type of construction where the fluid medium around thc pump or motor has access to the pistons, and furthermore by terminating short of the support member 4 the cylinder which is formed by the support frame 1 is capable of turning freely to adjust the stroke of the pistons. Because of the added rigidity provided by the side walls 14 the support frame is incapable of becoming deformed by high pressures in the fluid passages.

As has been indicated above, the structure of the invention is capable of being used for a swash-plate pump or motor. A swash-plate pump or motor of the open type which is described above and shown in the drawing is assembled into a larger container which holds in its interior a suflicient supply of oil. The entire pump or motor is immersed in this oil and in this way a uniform and sufficient cooling of the pump parts is provided. Such cooling is of particular significance for the bearings, and at the same time the cooling compensates for the different coeflicients of expansion of the different materials of which the several pump or motor parts are made. In particular, the pistons or piston rods of the open-type of swash-plate pump or motor turn in the oil bath in which the pump or motor is maintained so as to automatically provide a movement and mixing of the oil of the oil bath so that a uniform temperature distribution takes place throughout the oil of the oil bath. The temperature of the oil in which the pump or motor is located will in general be lower as the size of the container and the amount of oil therein is larger.

With pumps of the closed type the advantages discussed above of the open-type of pump or motor cannot be obtained, because the closed type of pump does not provide the possibility of mounting the pump in a bath of oil so that the inner parts of the pump are in engagement with the. oil bath. When these pumps of the closed type have a leakage of the oil at high pressure, and such leakage always takes place at the pistons as Well as at the control surface where the passages communicate with the cylinder bores, the oil which leaks has a high temperature and this temperature is higher as the pressure in the cylinder bores and passages increases. The oil at high pressure and high temperature of such a closed type of pump can be guided through leakage passages, but this does not provide a cooling of this oil, and certainly the cooling is not to the same extent as is provided with the open-type of pump described above. Experience has shown that 'with the closed type of pump the extremely high temperature of the oil leads to failures. In particular, those parts which are highly stressed develop scratches or cuts and become worn away, because the viscosity of the oil drops very sharply due to the high temperatures and the oil film is destroyed, so that the lubricating properties of the oil no longer exist. Such undesirable wearing and cutting or scratching of the surfaces of the parts of the closed type of pump take place particularly at the surfaces of the balls of the ball and socket joints, and also at the plain and roller bearings of the pump. Thus, with the closed type of pump it is in general not possible to operate at the same high pressure which can be used with the open-type of pump.

it is thus apparent that it is of advantage to use the open-type of pump or motor which is surrounded by a bath of oil so that damaging of the parts due to lack of lubrication cannot take place. However, up to the present time the open-type of pump has not been capable of being used satisfactorily because of the fact that the bearing flanges such as the bearing flanges 3 of FIGS. 1 and 2 become pressed away from each other due to the forces of the oil pressure and thus result in loss of oil. This disadvantage is eliminated by the present invention and it is therefore possible with the present invention to use the open-type of pump without encountering the d18- advantages heretofore present in such a pump or motor.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of pumps or motors diflering from the types described above.

While the invention has been illustrated and described as embodied in swash-plate pumps or motors, it is not intended to be limited to the details shown, since various modifications and structural changes may be made with out departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a swash plate pump or motor unit surrounded by a cooling fluid, in combination, a support member; a drive shaft turnably supported by said support member; a pair of coaxial bearing means fixedly carried by said support member and respectively arranged on opposite sides of said shaft; a frame member having an open end facing and spaced from said support member and having a pair of coaxial pivot pin portions projecting from opposite portions of said frame member and supported respectively in said bearing means so as to mount said frame member turnably about the axis of said bearing means, said bearing means and said pivot pin portions being formed with fluid passages therethrough for leading pressure fluid into and out of said unit; a cylinder drum rotatably supported by said frame member and operatively connected to said shaft and communicating with said passages for passing pressure fluid into and out of said cylinder drum when actuated by said shaft; and rigid means secured to and interconnecting said pair of hearing means on both sides of said frame member, said rigid means extending on opposite sides of a plane which coincides with the axis of said pivot pin portions and which is transversal to the axis of said shaft for preventing said bearing means from moving in axial direction relative to said frame member and to said pivot pin portions, said rigid means being spaced from said frame member and having a pair of edge portions concavely curved toward said support member so that said rigid means have a minimum width at portions thereof located substantially midway between said bearing means to permit tilting movement of said members relative to each other about the axis of said pivot pin portions and to permit flow of cooling fluid past said rigid means into said open end of said frame member.

2. An arrangement as defined in claim 1, in which said rigid means are fixed along one longitudinal side thereof to said support member and in which the other longitudinal side of said rigid means is concavely curved toward said support member.

3. In a swash plate pump or motor unit surrounded by a cooling fluid, in combination, a support member; a drive shaft turnably carried by said support member; a swash plate coaxial with and fixed to one end of said drive shaft for rotation therewith and located at one side of said support member; a pair of bearing means fixedly carried by said support member and respectively arranged on opposite sides of said shaft aligned along a common axis substantially normal to the axis of said shaft; a substantially cylindrical frame member having an open end facing and spaced from said swash plate and having a pair of coaxial pivot pin portions projecting from opposite portions of said frame member and resectively supported in said bearing means so as to mount said frame member tiltable about the axis of said hearing means from a position in which the axis of said frame member is aligned with said shaft axis to a position in which said axes include an obtuse angle with each other, said bearing means and pivot pin portions being formed with fluid passages therethrough for leading pressure fluid into and out of said unit; cylinder drum means coaxial with said frame member and supported for rotation about its axis by the latter and operatively connected to said swash plate for rotation therewith while pressure fluid is passed through said fluid passages; and a pair of elongated rigid members each fixed at opposite ends thereof to said bearing means, said rigid members being respectively located at opposite sides of the axis of said frame member and secured to said bearing means at opposite sides of a plane which coincides with the axis of said pivot pin portions and which is transverse to the axis of said frame member for preventing said bearing means from moving relative to said pivot pin portions under the pressure of the pumped fluid, each of said elongated members being fixed along one longitudinal side thereof to said support member and being on the other longitudinal side thereof concavely curved toward the latter so as to have a minimum width substantially midway between said bearing means, said bearing means and said elongated members forming an endless rigid structure about said frame member having its greatest length in direction of the axis of said bearing means and said rigid members being spaced from said frame member to permit tilting of said frame member about the axis of said pivot pin portions and to permit free flow of the cooling fluid surrounding the unit into the space between said swash plate and said open end of said frame member.

References Cited in the file of this patent UNITED STATES PATENTS 933,316 Macomber Sept. 7, 1909 1,020,285 Janney Mar. 12, 1912 2,155,455 Thoma Apr. 25, 1939 2,298,850 Vickers ct. 13, 1942 2,487,617 Tweedale Nov. 8, 1949 2,586,991 Postel Feb. 26, 1952 2,872,876 Thoma Feb. 10, 1959 

